For better practice, please print using "Actual size" as shown below.
So you do not print the margins.
Fold the A4 paper when practicing the questions and unfold to check the answers.

建议您选择“按实际大小打印”（如图所示）。这样避免了打印边框。
训练的时候可以折叠起来。对答案的时候可以打开。